1. Field of the Invention
This invention relates to a facsimile communication system in which facsimile terminals are connected via a telephone network. This invention specifically relates to a facsimile communication network system in which a central station including a picture store device serves to store picture information transmitted from facsimile terminals and to read out the stored picture information, and terminal adaptors indicate related communication charges.
2. Description of the Prior Art
In recent years, facsimile systems have been increasingly used, and large facsimile networks have been constructed. Some of facsimile networks include facsimile terminals and a facsimile store and conversion apparatus connected via telephone lines. Such facsimile networks are used in various ways. One example is a simultaneous multi-address transmission in which one facsimile terminal transmits common picture information to other facsimile terminals at a designated time. Another example is a mail box communication in which one facsimile terminal registers picture information into a store and conversion apparatus by using a predetermined ID (identification) number, and another facsimile terminal picks up registered picture information designated by the same ID number.
In a facsimile communication network system including facsimile terminals used by fixed subscribers, charges are monthly paid by the subscribers. In a facsimile communication network system including facsimile terminals used by unspecified persons, each user pays a charge for the related communication.
Japanese published unexamined patent application 1-226249 discloses a facsimile communication network system in which users pre-buy membership cards, and a user inserts his membership card into a facsimile terminal when using the facsimile terminal. Each membership card specifies a usable communication rate number, which is decremented each time the membership card is used to execute facsimile communication. The usable communication rate number is also decreased as the communication continues. In this prior art system, a user feels inconvenience when a usable communication rate number in his membership card is small but a large amount of picture information to be transmitted is present.